JPS6128531B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a four-wheel drive device with an automatic transmission, which is installed in the transmission system of a vehicle such as an automobile and comprises an automatic transmission and a front and rear wheel drive mechanism. Specifically, the present invention relates to a two-wheel drive transaxle automatic transmission combined with a four-wheel drive transfer mechanism.

[Conventional technology]

The so-called front engine/front drive (hereinafter referred to as FF), in which the engine is mounted in the front of the vehicle body and drives the front wheels, eliminates the need for a propeller shaft and drives and operates the front wheels. It has been widely used because it enables stable driving by facing the vehicle. and this
Even in the FF driving system, an automatic transmission is used in the transmission system to automatically change gears according to the driving condition of the vehicle. and a front wheel final reduction gear are integrally arranged in close proximity to each other.

By the way, in general, with two-wheel drive, the drive wheels tend to lose their grip ability, especially during low-speed, high-load operation such as sudden starts, rough roads, and uphill driving, and the vehicle performance cannot be fully demonstrated.
The present application is for a front-wheel drive device equipped with a manual transmission with a transfer mechanism for rear-wheel drive, which enables both front-wheel drive driving and front and rear four-wheel drive driving by manual operation. This method has already been proposed by someone (Japanese Unexamined Patent Publication No. 55-4292).

However, with the above-mentioned manual operation method using a mechanical dog clutch for the transfer clutch, operable conditions are limited to stopping with no difference in rotation between the front and rear wheels or driving straight ahead, resulting in problems in running performance. remains. On the other hand, since an automatic transmission is equipped with a hydraulic system as opposed to a manual transmission, it is conceivable to utilize the hydraulic system for the transfer mechanism as well.

For these reasons, the automatic transmission unit has four
When combining a wheel drive transfer mechanism, if a hydraulic clutch is installed in the transfer and the line pressure of the automatic transmission is used as the operating pressure for the clutch, FF (front wheel drive) (drive) or FR (rear wheel drive)←→4WD (4 wheel drive). In addition, by setting the operating conditions of the line pressure circuit switching valve for the clutch in advance, it is possible to automatically obtain 4WD (four-wheel drive) driving, which is extremely advantageous in terms of vehicle performance and operability. Become.

Therefore, conventionally, a hydraulic clutch was used as a transfer clutch of the above-mentioned four-wheel drive system with an automatic transmission.
There are various publications (prior art) of No. 39352. this is,
It is based on FR two-wheel drive, and in the transfer device located at the rear of the automatic transmission, the output shaft taken out from the rear of the transmission is permanently connected to the rear wheels. Further, a hydraulic clutch is attached to the output shaft side of the transmission, and transmission is configured from this hydraulic clutch to the front wheels via an output shaft that extends toward the front of the vehicle body, bypassing the chain transmission means, engine, and transmission.

[Problem that the invention seeks to solve]

Therefore, in the case of such a configuration, since it is an FR two-wheel drive, it is not possible to exhibit the power performance such as rough road running performance and cornering acceleration of a FF two-wheel drive, for example. Further, after the hydraulic clutch, the transmission system to the front wheels bypasses the engine and transmission, resulting in problems such as an increase in size and a complicated structure.

In view of these problems in the prior art, the present invention provides a four-wheel drive system based on two-wheel drive with an automatic transmission that has a compact transmission system for the rear wheels. The purpose is to provide a wheel drive device.

[Means for solving problems]

For this purpose, the present invention has an arrangement in which an oil pump is connected to the crankshaft of the engine, and a hydraulic control device is provided which is connected to the oil pump and changes oil pressure according to the load of the engine, and is connected to the crankshaft of the engine. and a first power transmission means that always directly transmits the output of the output shaft of the transmission to the front wheel final reduction gear,
A second power transmission that selectively transmits the output of the output shaft of the transmission to a rear wheel final reduction gear connected to a third power transmission means, and connected to the first power transmission means. a hydraulic transfer clutch having an input shaft and an output shaft is provided between the second power transmission means and the third power transmission means; The present invention is characterized in that the transmission torque of the hydraulic transfer clutch is made variable in accordance with the engine load, and is configured to be selectively transmitted to the rear wheel final reduction gear.

〔Example〕

Hereinafter, one embodiment of the present invention will be specifically described with reference to the drawings.

In FIGS. 1 and 2, reference numeral 1 denotes a front wheel drive device with an automatic transmission, which is roughly divided into a torque converter 2, an automatic transmission 3, a front wheel final reduction gear 4, and a hydraulic control device 5. A four-wheel drive transfer mechanism 6 is attached to the rear of the automatic transmission 3 of such a front wheel drive device 1 with an automatic transmission.

The torque converter 2 is, for example, a symmetrical three-element, one-stage, two-phase type, and includes a pump impeller 2a, a turbine 2b, and a stator 2c provided within a torque converter housing. The pump impeller 2a is connected to the engine crankshaft 8 via the drive plate 9.
directly connected to the turbine shaft 1 from the turbine 22b.
0 extends to the side of the automatic transmission 3 behind the torque converter. Then, by driving the pump impeller 2a with the engine power of the crankshaft 8 and rotating the turbine 2b while changing the oil flow with the stator 2c, the torque transmitted to the turbine shaft 10 together with the turbine 2b is increased according to the load. It is now possible to output power while An oil pump drive shaft 12 is coupled to the torque converter cover 11 that is integral with the drive plate 9, and this shaft 12 passes through the turbine shaft 10 to form an oil pump 13 disposed at the rear of the automatic transmission 3. is connected to drive it.

The automatic transmission 3 includes a Lavigneaux-type planetary gear 15 provided at the front inside the transmission case 14, and a low and reverse brake 1 at the rear thereof.
6, a forward clutch 17, a reverse clutch 18, etc. are arranged in sequence. The turbine shaft 10 from the torque converter 2 is connected to a forward sun gear 15a of a planetary gear 15 via a forward clutch 17, and at the same time to a reverse sun gear 15b via a reverse clutch 18 and a connecting shell 19. By hydraulically operating clutches 17 and 18, power from turbine shaft 10 is input to sun gears 15a and 15b. A brake band 20 is attached to a drum 18a integral with the connecting shell 19 of the reverse clutch 18, and by tightening this band 20 with hydraulic pressure, the reverse sun gear 15b is locked.

In the planetary gear 15, a short pinion 1 meshes with each sun gear 15a, 15b on the input side.
5c, the carrier 15e supporting the long pinion 15d is provided with the low and reverse brake 16, and the center support 21 is provided with the low and reverse brake 16.
A one-way clutch 22 is provided between the two, and the carrier 15c is locked by operation of the brake 16 or the one-way clutch 22.
And long pinion 15 of planetary gear 15
A ring gear 15f that meshes with the turbine shaft 10 is connected to an output shaft 23 coaxially arranged around the turbine shaft 10. In addition, the code|symbol 24 is a parking gear.

The front wheel final reduction gear 4 is disposed below the shafts 10 and 12 between the torque converter 2 and the automatic transmission 3, and includes a housing 7 and a case 14 thereof.
An output shaft 23 from the planetary gear 15 is mounted inside a case 25 mounted between the
It is taken out on the input side at the front of the vehicle and is rotatably supported. In addition, at the bottom of the output shaft 23,
A drive pinion 26 serving as a first power transmission means for transmitting the output of the transmission to the front final reduction gear is supported by bearings and arranged in parallel, and the output shaft 23 and the drive pinion 26 are connected by a set of reduction gears 27. Connected for power transmission, the drive pinion 26 meshes with a crown gear 29 of a differential mechanism 28 disposed below and orthogonally to the coaxially disposed shafts 10, 12, 23.

The four-wheel drive transfer mechanism 6 is provided inside an extension case 30 connected to the rear part of the transmission case 14, and a third drive shaft consisting of a rear drive shaft 31 is installed inside this case 30.
A power transmission means is arranged substantially coaxially with the shaft of the transmission and is rotatably provided. On the other hand, the first
A transfer drive shaft 33 serves as a second power transmission means for selectively transmitting the output of the drive pinion 26 as a power transmission means to the rear drive shaft 31. It is rotatably arranged on the extension line of the drive pinion of the machine 4, that is, between the automatic transmission 3 and the valve body 38 of the hydraulic control device, and the drive pinion 26 and shaft 33 are removably connected by a spline joint 32. Ru. The rear drive shaft 31 is provided with a hydraulic clutch type transfer clutch 35 similar to the clutches 17 and 18 of the automatic transmission 3, and its drum 35a is integrally connected to the rear drive shaft 31, and the hub 35b is connected to the rear drive shaft 31. It is connected to a transfer drive shaft 33 for power transmission via a set of transfer gears 34, and a propeller shaft 37 is connected to the rear end of the rear drive shaft 31 via a universal joint 36.

Further, the hydraulic control device 5 has various valves and oil passages inside a valve body 38 that is divided into upper and lower halves. It is installed horizontally inside an oil pan 39 installed under the transmission case 14, and regulates the hydraulic pressure generated by the oil pump 13 to control the torque converter 2 and the brake 1 of the automatic transmission 3.
6, the clutches 17 and 18, the servo means of the brake band 20, the transfer clutch 35 of the transfer mechanism 6, and furthermore, the lubricating parts are supplied.

Since the present invention is configured in this manner, engine power is constantly transmitted to the turbine shaft 10 via the torque converter 2 during engine operation.
In a low-speed operating state, the hydraulic control device 5 operates the forward clutch 17 to input power from the turbine shaft 10 to the forward sun gear 15a of the planetary gear 15, and the one-way clutch 22 locks the carrier 15e. , the rotational power with the largest gear ratio is taken out from the ring gear 15f to the output shaft 23, resulting in the first speed. After this shifting power is transmitted to the drive pinion 26 via the reduction gear 27, it is directly transmitted to the crown gear 29 of the differential mechanism 28 and further to the front wheels. On the other hand, the power of the drive pinion 26 is further transmitted to the transfer mechanism 6 via the spline joint 32 and the transfer drive shaft 33.

In such a state, when the engine load is small, when the transfer clutch 35 is released by the valve operation of the hydraulic control device 5, the transfer gear 34 and the rear drive shaft 31 are separated by the clutch 35, and the rear drive shaft 31 is disconnected. Power is no longer transmitted to the rear wheels after the shaft 31, resulting in FF two-wheel drive driving using only the front wheels.

On the other hand, when operating under high load at this time, when line pressure is supplied from the hydraulic control device 5 to the transfer clutch 35 to engage the drum 35a and the hub 35b, the transfer gear 34 is directly connected to the rear drive shaft 31. The power is then transferred to the rear drive shaft 3.
1 to the rear wheels via the propeller shaft 37, resulting in a four-wheel drive state in which the front and rear wheels are driven simultaneously.

Next, as the vehicle speed increases, the brake band 20 is operated by the hydraulic control device 5 to lock the reverse sun gear 15b, and the output shaft 23 is rotated from the ring gear 15f of the planetary gear 15.
Rotational power from a small gear ratio is extracted and automatically shifted to second gear. At this time, when the engine load decreases and the transfer clutch 35 is released again,
If power is no longer transmitted to the rear drive wheels 31 and after, and the vehicle was traveling in four-wheel drive, the state returns to FF traveling. Furthermore, the vehicle speed increases and reverse clutch 1
8 also operates, and when the planetary gear 15 is integrated by simultaneously receiving input from the two sun gears 15a and 15b, the turbine shaft 10 and the output shaft 23
The direct connection of the engine allows the engine power to be extracted as is,
In this way, the gear is automatically shifted to third gear.

Reverse speed is obtained by operating the reverse clutch 18 to input power to the reverse sun gear 15b of the planetary gear 15, and by operating the low and reverse brake 16 to lock the rear gear 15e. Incidentally, when the low and reverse brake 16 is operated instead of the one-way clutch 22 during the first speed to lock the carrier 15e from reversing, the engine brake becomes effective.

When turning in a four-wheel drive state, torsional torque is generated in the transmission system of the front and rear wheels, but in this case, returning to the accelerator reduces the engine speed and the hydraulic pressure of the hydraulic control device 5, so the transfer The hydraulic pressure acting on the clutch 35 decreases. Therefore, the torsional torque generated in the transmission system of the front and rear wheels is absorbed by the transfer clutch 35, and the so-called tight corner braking phenomenon is avoided.

〔Effect of the invention〕

As explained above, according to the four-wheel drive system of the present invention, in a system that performs four-wheel drive using the rear wheels based on a vertical transaxle type FF two-wheel drive system with an automatic transmission, when two-wheel drive the FWD It can demonstrate excellent performance such as ability to travel on rough roads. A second power transmission means is connected to the first power transmission means connected to the front wheel final reduction gear, and a third power transmission means transmits power to the second power transmission means and the rear wheel final reduction gear. A hydraulic transfer clutch with one input shaft and one output shaft was installed between the This is advantageous in that the low center of gravity provides excellent high-speed stability, especially when converting passenger cars to four-wheel drive.

Furthermore, in the case of a FF vehicle, the second power transmission means can be removed from the first power transmission means, and the transaxle portion can be completely shared, so compatibility with FF vehicles is very good.

Furthermore, in order to prevent tight corner braking when cornering in four-wheel drive mode, the transmission torque of the hydraulic transfer clutch using the output oil pressure of the hydraulic control device is made variable according to the engine load, and the rear wheel Since the transfer clutch is configured to selectively transmit the torque to the final reduction gear, the clutch slips due to a drop in hydraulic pressure in the transfer clutch and absorbs the torsional torque generated on the drive shafts of the front and rear wheels. It can be avoided.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment of a four-wheel drive device with an automatic transmission according to the present invention, and FIG. 2 is a skeleton diagram schematically showing the same device. DESCRIPTION OF SYMBOLS 1...Front wheel drive device with automatic transmission, 2...Torque converter, 3...Automatic transmission, 4...Front wheel final reduction gear, 5...Hydraulic control device, 6...Transfer mechanism, 26...Drive Pinion, 31... Rear drive shaft, 32... Spline joint, 33...
...Transfer drive shaft, 34...Transfer gear, 35...Transfer clutch, 38...
...Valve body.

Claims (1)

[Scope of Claims] 1. An oil pump is connected to the crankshaft of the engine, and a hydraulic control device is provided which is communicated with the oil pump and changes the oil pressure according to the load of the engine,
A transmission connected to the crankshaft of the engine, and a first power transmission means for directly transmitting the output of the output shaft of the transmission to the front wheel final reduction gear at all times, the output of the transmission a second power transmission means that selectively transmits the output of the shaft to a rear wheel final reduction gear connected to a third power transmission means and is connected to the first power transmission means; A hydraulic transfer clutch having one input shaft and one output shaft is provided between the second power transmission means and the third power transmission means, and the hydraulic transfer clutch is controlled by the output hydraulic pressure of the hydraulic control device. A four-wheel drive system with an automatic transmission, characterized in that the transmitted torque is made variable in accordance with the load of the engine, and is configured to be selectively transmitted to a rear wheel final reduction gear.